The invention relates to an automotive electrical alternator, and particularly to an alternator having coolant channels adapted to pass liquid engine coolant through the alternator for cooling the alternator.
This invention is related to an electrical alternator, particularly adapted for use in motor vehicle applications including passenger cars and light trucks. These devices are typically mechanically driven using a drive belt wrapped on a pulley connected to the crankshaft of the vehicle""s internal combustion engine. The belt drives a pulley on the alternator which rotates an internal rotor assembly to generate alternating current (AC) electrical power. This alternating current electrical power is rectified to direct current (DC) and supplied to the motor vehicle""s electrical bus and storage battery.
While alternators have been in use in motor vehicles for many decades, today""s demands on motor vehicle design, cost, and performance have placed increasing emphasis on the design of more efficient alternators. Today""s motor vehicles feature a dramatic increase in the number of electrical on-board systems and accessories. Such electrical devices include interior and exterior lighting, climate control systems; increasingly sophisticated powertrain control systems, vehicle stability systems, traction control systems, and anti-lock brake systems. Vehicle audio and telematics systems place further demands on the vehicle""s electrical system. Still further challenges in terms of the output capacity of the motor vehicle""s electrical alternators will come with the widespread adoption of electrically assisted power steering and electric vehicle braking systems. Compounding these design challenges is the fact that the vehicle""s electrical system demands vary widely, irrespective of the engine operating speed which drives the alternator and changes through various driving conditions.
In addition to the challenges of providing high electrical output for the vehicle electrical alternator, further constraints include the desire to minimize the size of the alternator with respect to under hood packaging limitations, and its mass which relates to the vehicle""s fuel mileage.
Further, designers of these devices strive to provide high efficiency in the conversion of mechanical power delivered by the engine driven belt to electrical power output. Such efficiency translates directly into higher overall thermal efficiency of the motor vehicle and thus into fuel economy gains. And finally, as is the case with all components for mass-produced motor vehicles, cost remains a factor in the competitive offerings of such components to original equipment manufacturers.
One concern with higher power producing alternators is heat production. Fans mounted on the front of the alternator will circulate air across the front side to help cool the alternator, however, with higher output alternators, there is too much heat produced to be dissipated by these fans. Liquid cooled alternators dissipate the heat more effectively, but require extra size to accommodate cooling flow channels. A related issue is noise generation. Air cooled alternators generate fan noise, which may be objectionable to vehicle occupants. Liquid cooling of alternators is a known technique for making alternators more quiet than air cooled alternators.
Therefore, there is a need for an improved alternator having flow channels to allow the alternator to be liquid cooled while still maintaining a small compact size.
In a first aspect of the present invention, an alternator includes an inner housing and an outer housing mounted over the inner housing with a pair of o-rings positioned therebetween to define a sealed flow chamber having a first plenum, a second plenum, and an axial jacket interconnecting the first and second plenums.
In another aspect of the present invention, the first plenum is defined by opposing first and second disk shaped portions of the inner housing, such that the first plenum is a disk shaped cavity extending diametrically across the alternator adjacent a rear end of the alternator. The axial jacket is defined by an inner diameter of the outer housing and an outer diameter of the inner housing, such that the axial jacket forms an annular jacket extending entirely around the alternator. The second plenum is defined by a second disk shaped portion of the inner housing an a disk shaped front portion of the outer housing, such that the second plenum is a disk shaped cavity extending diametrically across the alternator adjacent a front end of the alternator.
In still another aspect of the present invention, an inlet extends from the first plenum and is adapted to allow coolant to enter the first plenum and an outlet extends from the second plenum and is adapted to allow coolant to exit the flow chamber.
In yet another aspect of the present invention, an arcuate notch is formed within the first disk shaped portion of said inner housing defining a first passageway interconnecting the first plenum and the axial jacket and an arcuate notch is formed within the third disk shaped portion of the inner housing defining a second passageway interconnecting the axial jacket and the third plenum. The inlet is positioned diametrically across from the first passageway such that coolant entering the inlet must flow diametrically across the alternator to reach the first passageway. The first passageway is positioned diametrically across from the second passageway such that the coolant entering the axial jacket must flow annularly around the alternator to reach the second passageway. The outlet is positioned diametrically across from the second passageway such that coolant entering the second plenum must travel diametrically across the alternator to reach the outlet.
In yet another aspect of the present invention, the inlet and the outlet are adapted to connect to a coolant system of an automobile such that engine coolant is circulated through the alternator.